Heat and gas supply, ventilation and air-conditioning

5)any device for compressing, driving, raising, or reducing the pressure of a fluid, esp by means of a piston or set of rotating impellers;

6)a device for heating a room, building, etc., consisting of a series of pipes through which hot water or steam passes;

7)a flow of electric charge through a conductor;

8)a strong thick rope, usually of twisted hemp or steel wire;

9)a device that maintains a system at a constant temperature. It often consists of a bimetallic strip that bends as it expands and contracts with temperature, thus breaking and making contact with an electrical power supply.

18. Fill in the correct prepositions, translate the phrases, then choose any five items and make up the sentences of your own.

1) to differ ___ the way; 2) to circulate steam ___ pipes; 3) to give

___heat; 4) to warm the air ___ a furnace; 5)to force air ___ a system of pipes ___each room; 6) to carry air ___the rooms back ___the furnace; 7) to remove dust particles ___ the air; 8) to have certain advantages ___

smth.; 9) a network ___ pipes; 10) the air ___ knee height, ___the ceiling and ___ floor level; 11) to equalize temperature ___ a room; 12) to be installed ___ the skirting boards of a room; 13) to limit the temperature difference ___ the floor and the ceiling ___ only a few degrees; 14) to produce heat ___ passing electricity ___ a material; 15) to produce heat

___ electricity; 16) to be controlled ___ thermostats. READING TASK: Text 2

19. Read the title of the following text. What can this text deal with? What are the main central heating systems? Read the text and check.

Central Heating Systems

There are two main kinds of central heating systems direct and indirect. They differ in the way they distribute heat. A direct system circulates the warm air throughout the area being heated. An indirect system circulates steam or hot water through pipes to convectors or radiators, which give off heat.

A warm-air heating system (WAHS) warms the air in a furnace and then forces it through a system of ducts (pipes) to each room. Another

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system of ducts carries cool air from the rooms back to the furnace. An electrically driven blower in the furnace moves the air through the ducts, and filters remove dust particles from the air. The ducts and blower can be used as part of a central air-conditioning unit.

Steam and hot-water heating systems (SHWHS) are used in many large buildings. These systems cost more than warm-air systems, but they have certain advantages over them. The pipes carrying steam or hot water are smaller than warm-air ducts and thus take up less space. Automatic valves can control the amount of hot water or steam flowing to convectors more easily than they can control warm air. Thus, it is easier to control the temperature in different rooms with these systems than with warm-air heating.

A steam heating system requires a boiler, and a hot-water heating system has a hot-water heater, also called a boiler. Fuel burning in the boiler produces heat for the system. The system also has a network of pipes and convectors. In steam heating, a condensate pump forces the condensed steam back to the boiler. In hot-water heating, a pump circulates the water through the system.

The convectors of a steam or hot-water system, often called radiators, give off most of their heat by convection and radiation. The amount of heat given off by radiation depends on the temperature of the converter and its surface area. The more metal that is exposed, the more heat is given off.

One difficulty in heating with high temperature convectors is that the air near the ceiling becomes warmer than the air in other parts of the room. For example, the air at knee height may be 16°C, the air at breathing level may be 20°C, and the air at the ceiling may be 24°С.

Radiant heating is a method of equalizing temperature within a room. A continuous loop of hot-water pipe or electric cable is installed in the ceiling or floor. Heat leaves the pipe or cable by radiation, which does not directly raise the temperature of the air within a room. Radiation affects only the objects it strikes, and so it produces more uniform heating than convection does.

Radiant heating may also be installed along the skirting boards of a room. All radiant heating systems limit the temperature difference between the floor and the ceiling to only a few degrees.

Electric heating differs from other central systems because it requires no combustion of fuel in the building being heated. The fuel used to make electricity is burned at an electric power plant that may be far

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away. Electric heat is produced by electric heating units. Such units produce heat by passing electricity through a material that resists the flow of current. This type of heating, called resistance heating, produces much radiant heat. Such heat warms the surface of the skin and clothing and makes people feel comfortable even in a cool room. Radiant electric heating uses a cable that produces heat from electricity. An electric heating unit can be placed in the ceiling, skirting boards, floor, or wall. The temperature can be controlled by thermostats in each room, or area.

COMPREHENSION CHECK

20. Decide whether the following statements are true or false according to Text 2.

1)There are two types of heating systems which differ in the way they circulate the warm air.

2)A direct system and indirect system both circulate the warm air.

3)A direct system circulates steam or hot water to convectors or radiators.

4)SHWHS are cheaper than WAHS.

5)SHWHS are used mainly in private homes.

6)It is easier to control the temperature with SHWHS than with warmair heating.

7)Radiators give off heat in two ways.

8)The amount of heat given off by a convector depends upon the temperature of the convector.

9)Electric heating doesn’t differ from other central systems.

10)The fuel is burned at an electric power plant that must be situated close to the building being heated.

11)The temperature can be controlled by thermostats in electric heating.

12)An electric heating unit can not be placed in walls.

21. Choose the main advantages of the radiant heating system.

1)it affects only the objects it strikes;

2)it can be combined with air-conditioning system;

3)it provides comfort at a lower room temperature than other heating systems;

4)it distributes heat evenly;

5)it removes dust particles from the air.

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22. Answer the following questions and give examples.

1)Where does a warm-air heating system (WAH) warm the air?

2)How does it transmit warm air to each room?

3)What is the function of filters?

4)Can WAH be used as a part of an air-conditioning unit?

5)What are the main parts of a steam and hot-water heating system?

6)What is the function of a radiator?

7)What is radiant heating?

8)Why does electric heating differ from other central systems?

9)What are the peculiarities of electric heating?

23. What types of heating are pictured? Fill in the schemes with the correct words from the text.

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24. Fill in the following table summarizing the whole information of Text 2.

25. Write a summary of Text 2.

OVER TO YOU

26. Discuss with your groupmates or in pairs: what central heating systems are commonly used in Belarus? Where are they used? What heating system is the most suitable / advantageous for you?

ACTIVE VOCABULARY

27. Give Russian equivalents of the following words and phrases. Try to memorize them.

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28. Match the English and Russian equivalents.

29. Make sure you know the verbs formed from the following nouns.

30. Combine the words from the column on the left with the suitable nouns from the column on the right. Translate them into Russian.

31. Match the words with their synonyms.

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32. Fill in the correct prepositions, translate the phrases, then choose any five items and make up the sentences of your own.

1) ___ favor of water-on-demand; 2) a drum filled ___ water; 3) to be equipped ___ a heating mechanism; 4) to deliver hot water right ___

your faucet; 5) to enter the water heater ___ the dip tube; 6) to have a separate thermostat ___ each element; 7) to move the tank ___ another location; 8) to keep the pressure inside the water heater ___ safe limits; 9) to provide ___ hot water; 10) to rely ___ the principle.

READING TASK: Text 3

33. What are the main parts of a water heater? Read the text below to check your answer.

Inside a Water Heater

Water heaters are familiar fixtures in most homes. They typically look like big metal cylinders, tall drums that are often consigned to a laundry room or basement. Newer styles have some interesting features, like losing the tank completely in favor of water-on-demand, but the old, reliable water heater design that's most widely used today is really a pretty simple appliance; it's basically a drum filled with water and equipped with a heating mechanism on the bottom or inside. Even though they lack drama and complexity, water heaters are still pretty amazing. What makes them interesting is that they exploit the heat rising principle to deliver hot water right to your faucet with a minimum of fuss. Water heaters have an ingenious design on the inside for something that looks so ordinary on the outside.

Let's take a quick look at the components that work together in your water heater:

Tank – The inner shell of a water heater is a heavy metal tank containing a water protective liner that holds 151 to 227 liters of hot water at around 50 to 100 pounds per square inch (PSI), within the pressure range of a typical residential water system. The exterior of the tank is covered in an insulating material like polyurethane foam. Over that, there's a decorative outer shell and possibly an additional insulating blanket.

Dip tube – Water enters the water heater through the dip tube at the top of the tank and travels to the tank bottom where it's then heated.

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Shut-off valve – The shut-off valve stops water flow into the water heater. It's a separate component from the heater located outside and above the unit.

Heat-out pipe – Suspended toward the top of the tank's interior, the heat-out pipe allows the hot water to exit the water heater.

Thermostat – This is a thermometerand temperature-control device. Some electric water heaters have a separate thermostat for each element.

Heating mechanism – Electric water heaters have heating elements inside the tank to heat the water. Gas water heaters use a burner and chimney system instead.

Drain valve – Located near the bottom of the exterior housing, the drain valve makes it easy to empty the tank to replace the elements, remove sediment or move the tank to another location.

Pressure relief valve – This safety device keeps the pressure inside the water heater within safe limits.

Sacrificial anode rod – Made of magnesium or aluminum with a steel core, the sacrificial anode rod is suspended in the water heater tank to help retard corrosion.

Now, let's see how all these parts work together to provide you with hot water.

A water heater's thermostat controls the temperature of the water inside the tank. Normally, you can set the temperature anywhere between 49 to 82 degrees Celsius. The water temperature setting recommended by most manufacturers is between 49 to 60 degrees Celsius. This is hot enough to be efficient for household use, but not so hot that it can pose a scalding risk. If there are children living in your home, it's wise to stay closer to the lower end of the range.

Setting your water heater to a lower temperature saves energy, too. Usually, the thermostat is located underneath a protective cover plate and has a knob or dial you can turn to set the temperature.

The dip tube feeds cold water from your home's water lines to the bottom of the tank's interior, where the water starts to warm up. The heating mechanism, either a burner or an element, stays on until the water reaches temperature. As the water heats, it rises to the top of the tank. The heat-out pipe is located near the top of the tank. Water exiting the water heater at the top is always the hottest in the tank at any given moment because it's the nature of hot water to rise above denser, cold water.

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COMPREHENSION CHECK

34. Complete the following sentences according to Text 3.

1)Water heaters typically look like …

2)Water heaters exploit the heat rising principle to deliver …

3)The inner shell of a water heater is …

4)Water enters the water heater through …

5)The heat-out pipe allows the hot water to …

6)The drain valve is located …

7)Pressure relief valve keeps the pressure inside the water heater within…

8)You can set the temperature anywhere between …

9)The thermostat is located …

35. Decide whether the following statements are true or false according to Text 3.

1)The old, reliable water heater design includesa drum filled with water and equipped with a heating mechanism on the bottom or inside.

2)The exterior of the tank is covered in a protective material.

3)The shut-off valve is located inside and above the unit.

4)Electric water heaters have a burner and chimney system inside the tank to heat the water.

5)Sacrificial anode rod helps to retard corrosion.

6)The secret to a water heater's design for separating cold water from hot relies on the heat rising principle.

36. Answer the following questions and give examples.

1)What interesting features have newer styles of water heaters?

2)How many liters of hot water does a tank hold?

3)What stops water flow into the water heater?

4)What is a thermostat?

5)What are the functions of a drain valve?

6)What is a sacrificial anode rod made of?

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